Steam generator



J. F. OTIS STEAM GENERATOR MaL a, 1927.

lFiled June 28-. 1920 er tube Patented May 3, 1927.

UNITED STATES,

PATENT, OFFICE.

JOHN rmcrs one, or oswneo, NEW Yonx. arm emmroa.

Application filed June 28, 1820, Serial No. 892,402. Renewed February 21,1927.-

This invention relates to certain improve ments in steam generators; and the objects and nature of the invention will be readily understood by those skilled in the art in the light of the following explanation of the accompanying drawings illustrating what I now believe to be the preferred embodiment of the invention from among other forms, constructions and arrangements within the spirit and scope thereof.

The steam generator of this invention is particularly intended for use where a comparatively small compact structure is required to operate under high temperature to evaporate a comparatively large volume of water per unit of time. Generators of this type usually embody a steel shell and 8 a comparatively large number of small diameter copper fire tubes. Often such generators are under six feet in vertical length (including the fire box) with tube sheets under five feet in diameter and carrying over a thousand approximately half inch copper fire tubes approximately less than three feet in length and, are required to evaporate approximately two hundred and fift gallons of Water per hour.

urning or injury of the lower end por tions of the fire tubes and cutting or loosening of the fire tubes in the tube sheets, have constituted serious difliculties in the operation of boilers of this type, and these troubles have been .due to excessive evaporation at the top surface of the bottom tube sheet under the intense heat of the oil burner flame and to the employment of the great mass of copper fire tubes in connection with-a generator" shell composed of metal other than copper, usually of steel.

It is the object of my invention to provide exceedingly simple, durable, economical and effective means for reducing these difiiculties to the minimum by providing a firei tube-protecting supply of water on the lowsheet and by rendering the shell longitudinally expansible and contractile approximately with the fire tubes, all by means of a peculiar shell formation.

With these and other ends in view, my invention consists in certain novel features in construction, and in combinations and larged or flared outwardly The bottom tube arrangements as more fully and particularly set forth and specified hereinafter. eferrlng to the accompanying drawmgsz- The single figure shows a steam generator, embodying myinvention, in longitudmal section. i

In the drawings, I show a generator of the type hereinbefore mentioned and um bodylng an upright approximately cylindrical boiler shell 1;top tube sheet 2; bottom tube sheet 3; the mass of vertical fire tubes 7 at their lower ends opening into a combustion chamber surrounded by the water leg 5 and at their up er ends openmgs into a combustion cham r under hood he generator is mounted on a suitable base providing a burner chamber 9 lined with fire brick or refractory material.

The Water supply for the generator enters the lower end portion of the water leg 5 through-feed Water pipe 0.

The steam after passing through any suit able separator late 13 within the steam space of the boi er, leaves the boiler through steam pipe 10, superheater 11, and ofl'take pipe 12, or by any other suitable means or in any desirable manner.

vIn the embodiment illustrated, the top tube-sheet 2 is flat and reater in diameter than-the steam space 0 welded, rivetedor otherwise secured at 21 on the out turned or flanged top end of the shell. The upper end of the shell is enon curved'lines and terminates in the annular external horizontal flange 20 on which the top tube sheet is secured to form a tight joint. The arrangement of this tube sheet and the shell at this point, and the shell flare, provide for longitudinal expansion of the shell with respect to the portion of the tube sheet receiving the tubes, or in other words, an expansion joint or longitudinally expansible connection is established between the cylindrical portion of the shell below said flare and the tube-receiving portion of said sheet. .sheet is bent to form depending annular 'wall 4 cooperating with the lower end portion of the shell 1 to form water leg 5, of substantial capacity and the the boiler and is pansible connection- 1 termediate annular joints.

- lower end of wall 4 is flanged at 6 and welded or riveted to the shell to form a tight joint and to close the bottom of thewater leg; and also to form a longitudinally exbetween the shell and bottom tube sheet, particularly with respect to the portions of the tube sheets that receive the tubes. In the embodiment illustrated, the boiler shell is formed without inbe formed by rolling or otherwise manipulating orbending a single sheet to produce the shapes desired, or if. the shell is made u of several sheets riveted or welded to- 15 gether (in this embodiment). I do not show distinct upper and lower sections united by an annular intermediate expansion joint, although I do not Wish to limit all features of my invention to the one-piece 20 shell as thus defined. The one-piece shell,

7 as thus defined, is rolled or otherwise bent to form an intermediate longitudinally ex- 'pansible portion which also constitutes a water deflector.

In' the example illustrated,"the diameter of tlie portion of the shell surrounding. the water leg, exceeds the diameter of the cylindrical portion of the shell that surrounds the space occupied by the fire tubes, and the diameter'of said upper ortion exceeds that of the intermediate portion of the shell that forms said annular deflector and expansible portion. In the form shown by the accompanying drawings, said intermediate portion constitutes an annular inward contraction orbulge 25 on curved lines and approximately U-shaped in cross section. At the lower end of this contraction, the shell starts to contract inwardly and upwardly at the upper portion of the water leg and ina horizontal plane plane of the horizontal tube-receiving portion of the lower tube sheet. The upwardly inwardly curving lower wall or side 25% of the contraction extendsinwardly over the water leg and over and above the lower tube sheet and thereby contracts the upper end of the water leg and in connection with the top surface of said tube sheet forms an annular mouth 25 for the water leg that opens or is directed approximately horizontally and inwardly toward the center of the water space on the top surface of said sheet. The contraction from thence curves upwardly and outwardly to form the top side or wall 25 of the contraction which gradually merges upwardly on curved lines into the upper cylindrical wall of the shell. The inner surface 25 of the floor or approximate vertical portion of this bulge 25' approximately approaches the outer fire tubes, i. e. approaches as close as ossible to said tubes without contracting t e same under all conditions of expansion and contraction. In other words, the bulge at its point 25 of intermediate expansible portion,

The shell may below the horizontal smallest internal diameter, is located a comparatively short distance above the horizontal top surface of the lower tube sheet and is as close as possible to the outer fire tubes without actually contacting the same. This bulge formation provides the shell with an to aid in rendering the shell longitudinally elastic or expansible with respect to the tube-receiving portions of the tube sheets so that the shell can expand and contract with said tubes to reduce to' the minimum danger of the joints betweenithe tubes and sheets becoming loose or damaged by reason of unequal expansion and contraction between the tubes and shell.

This bulge also by reason of its relation with respect to the water leg and bottom sheet, sets up and maintains an inward flow of water on the top surface of said tube sheet to protect the lower end portions of the tubes, particularly the inner or central tubes. The boiler water supply enters the water leg and consequently there is a constant flo'w of water from said leg, and the mouth of the leg is so formed b the bulge as to hold the water down on sai tube sheet and direct the same inwardly 1n the mass of tubes. This action is aided by the close approach of the bulge to the tubes, particularly as the top side or wall of the bul e also directs the water flowing down at t e.

cations and variations might be resorted to without departing from the spirit and scope of my invention and hence I do not wish to limit myself to the exact disclosures hereof.

What I claim is 1. A steam generator having a water leg provided with the feed water inlet, and emodying upper and lower tube sheets, fire tubes j ining said sheets, and an enclosing single-section shell joining said tube sheets, said shell formed with an intermediate inward annular bulge closely approaching the tubes without contacting the same and extending inwardly over the water leg and over and approaching the bottom flue sheet to cooperate therewith formin the water leg with an annular contracte top mouth opening inwardly above the bottom sheet to maintain a flow of water from the leg inwardl on the flue sheet, the upper SlClG of said bulge arranged to direct'water flowing down above the bulge inwardl among the tubes, said bulge forming the s ell with an intermediate longitudinally expansible portion.

2. A steam generator having an annular ing said sheets and constituting the sole connection between said sheets within the generator, and an outside shell, said shell formed with a curved intermediate annular inward. bulge ormntraction overhangin the bottom sheet and the water. leg and as c osely surrounding the mass of tubes as possible without contacting the same and 1n conjunction with the bottom sheet. forming a vertically contracted and inwardly extend-- ing discharge mouth from the water 1e the internal diameter of the sheet at said% being less than the internal diameters of the shell above'a'nd below said bulge, said bulge providin the shell with a longitudinally expansibFe portion. l-

JOHN FRANCIS OTIS.

ulge 10' 

